1. Field of the Invention
The present invention relates to a display device, and more particularly, a data converting apparatus for a display device.
2. Background of the Related Art
Contrary to a common monitor where analog signals are input, digital signals corresponding to a display resolution are input in a general liquid crystal display (LCD) device. However, when data is transmitted by a connection between systems, the display format should be converted due to difference between a resolution of an input image data and a resolution of an LCD screen.
FIG. 1 shows a diagram of a conventional LCD device and FIG. 2 shows a state of a display when a low resolution screen is realized using a partial cell expansion of the conventional technology. A color LCD display control system similar to FIG. 1 is illustrated in U.S. Pat. No. 5,448,260.
When an LCD device is a VGA having the resolution of 640.times.480, no problem occurs due to a resolution difference between the input image data and the image displayed on the LCD device. However, in the case of a high resolution of 800.times.600, 1024.times.768 and 1280.times.1024, the conversion of a low resolution input image data to a high resolution display format is difficult, because the ratio of resolutions between the LCD device and image data are not an integral proportion.
A method to solve the above problems in converting the display format is to display an image by partially using a display area of an LCD screen, not the overall area. FIG. 1 shows a display an image using a partial display area of an LCD screen. Since the number of pixels is small, the screen display area is partially used to display a low resolution image data.
In FIG. 1, the image data of 640.times.480 is displayed in an LCD device having a resolution of 800.times.480. Here, the ratio of a screen usage is 64%. Each of the column drivers and gate drivers selectively outputs a driving signal in accordance with a column control signal and a gate control signal, respectively, provided from a controller to display the low resolution RGB image data from a system, e.g., a personal computer. The display format converting method of FIG. 1 is the same as that of performing a display through assignment by the controller a start point and an end point in accordance with a resolution of image data input as 800.times.600 pixels. Accordingly, the pixels at a peripheral portion of an LCD screen display area are selectively used to display the input image data.
In the display format converting method described above, the screen of the LCD is inefficiently used. When image data having a 640.times.480 resolution is displayed on the LCD having an 800.times.600 resolution, only 64% of the LCD screen area is used.
Another method to solve the above problems is to reconstruct the screen and displaying the same using a CPU or a VGA chip in a video card driver or a video card. FIG. 2 shows a conversion of a display format by partially amplifying a cell. When a RGB image data having a resolution of 640.times.480 is displayed on an LCD device having an 800.times.600 display resolution, the ratio of resolution is 5:4. However, in this method, the image data corresponding to a single cell among arbitrary four cells of a 640.times.480 mode is amplified twice to convert the image data for display as a 800.times.600 display format.
In the second method of displaying by amplifying twice the image data of the arbitrary number of pixels, the quality of an image is deteriorated due to the difference between an amplified pixel and the neighboring pixels. As shown in FIG. 2, in a converted image where a particular pixel in an original image is amplified, a portion having the amplified pixel seems much darker.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.